1. Field of the Invention
The present invention relates to a liquid recording material which may be used as a liquid developer such as an electrophotographic developer, for use in wet-type recording apparatus such as an electrophotographic apparatus, a printer, or for use in ink-jet recording apparatus, and which liquid recording material may also be used as a printing ink.
2. Discussion of Background
It is conventionally known that silicone resin is used as a component for an electrophotographic developer. For example, in Japanese Laid-Open Patent Application 53-57039, there is disclosed a development method conducted by coating a development roller with a liquid developer with a viscosity of 3 to 1,000 cp, a solid component content of 0.5 to 50 wt. %, and a particle size of 0.5 to 5 μm (silicone toner with high viscosity and high solid component content, containing silicone oil with high viscosity).
Japanese Laid-Open Patent Application 3-171149 discloses a silicone toner prepared by using a vinyl polymer which contains a cross-linking agent in an amount of 0.005 wt. % or more.
Japanese Laid-Open Patent Application 3-171150 discloses a silicone toner which contains a rosin-based polymer with a molecular weight of 2000 to 40000 and a softening point of 50 to 190° C.
Japanese Laid-Open Patent Application 3-171151 discloses a silicone toner prepared by using a polymer which is prepared by cross-linking a carboxyl-group-containing vinyl polymer with amine.
Furthermore, Japanese Laid-Open Patent Application 3-200263 discloses a silicone toner which contains erucamide.
Japanese Laid-Open Patent Application 3-200264 discloses a silicone toner containing a vinyl polymer with a weight-average molecular weight/number-average molecular weight ratio of 4 or more.
Japanese Laid-Open Patent Application 3-200265 discloses a silicone toner comprising a self-crosslinking polymer and a crosslinked polymer.
Japanese Laid-Open Patent Application 3-225356 discloses a silicone toner comprising a crosslinked polyester.
Japanese Laid-Open Patent Application 3-225357 discloses a silicone toner prepared by using a polymer with part of a main chain or a side chain thereof being connected by an acid-base mutual action.
Japanese Laid-Open Patent Application 3-225358 discloses a silicone toner prepared by using a methylol-group-containing resin and a resin which is reactive with the methylol-group-containing resin.
Japanese Laid-Open Patent Application 3-225361 discloses a silicone toner comprising a polyolefin with a melt index of 25 to 700.
Japanese Laid-Open Patent Application 3-225364 discloses a silicone toner comprising a polyolefin with an AV of 0.5 or more, and a melt viscosity of 50 to 15,000 cp at 200° C.
Japanese Laid-Open Patent Application 4-88357 discloses a silicone toner with a viscosity of 1 to 50 cp at 100° C. and a critical surface tension of 18 to 36 dynes/cm when the solid component thereof is 10 wt. %.
Japanese Laid-Open Patent Application 3-199204 discloses a toner prepared by using a silicone oil as a polymerization catalyst.
Japanese Laid-Open Patent Application 3-223302 discloses a method of producing a toner by polymerizing a toner preparation material which is prepared by dissolving or dispersing a vinyl monomer in a silicone oil with a viscosity of 10000 CS or less.
Japanese Laid-Open Patent Application 3-292352 discloses the use as a toner of a non-aqueous dispersion liquid which contains a polymer which is prepared from at least (a) one resin which is insoluble in silicone oil and (b) a monomer which dissolves the resin.
Japanese Laid-Open Patent Application 3-171152 discloses a toner composed of a fluorine-based solvent, an aliphatic hydrocarbon and a silicone solvent.
Japanese Laid-Open Patent Application 4-199064 discloses the use of a concentrate toner by diluting the concentrate toner with a dilution liquid comprising as the main component a silicone oil.
Japanese Laid-Open Patent Application 53-57039 discloses a silicone toner with a viscosity of 3 to 1000 CS, a solid component content of 0.5 to 50 wt. %, and a particle size of 0.3 to 5 μm.
Japanese Laid-Open Patent Application 3-199204 and Japanese Laid-Open Patent Application 3-223302 disclose a method of producing a toner by polymerizing a vinyl monomer in silicone oil.
Furthermore, there is known an electrophotographic liquid developer which is prepared by dispersing a toner which comprises as the main components a thermoplastic resin such as styrene resin or acrylic resin, and a coloring agent comprising a pigment such as carbon black or a dye, in a carrier liquid such as silicone oil, vegetable oil, or an aliphatic hydrocarbon solvent as disclosed, for instance, in Japanese Laid-Open Patent Application 55-35321.
As a recording method, using the above-mentioned liquid developer, there is known an intermediate-image-transfer recording method comprising the steps of forming a latent electrostatic image on the surface of a photoconductor, developing the latent electrostatic image to a visible toner image with the liquid developer, transferring the toner image to an intermediate image transfer belt, and transferring the toner image to a recording sheet, as disclosed, for instance, in U.S. Pat. No. 4,708,460.
A method of directly transferring the toner image to the recording sheet, without using the intermediate image transfer belt, is also known. In ink-jet inks and printing inks, water, various solvents, coloring agents, resins and dispersing agents are used.
The above-mentioned conventional recording methods using the liquid developers have the problems that when the boiling point of the carrier liquid for use in the developers is high, for instance, when an aliphatic hydrocarbon solvent such as silicone oil or a vegetable oil is used as the carrier liquid, the carrier liquid is held on the image transfer sheet and is difficult to evaporate, and the odor of the carrier liquid stays particularly when the boiling point of the carrier liquid is high, and that image fixing cannot be performed properly.
The above-mentioned intermediate-image-transfer recording method has the shortcomings that image transfer efficiency is low, images with sufficiently high density cannot be obtained on a recording paper, and images with clear contours cannot be obtained.
In the above-mentioned intermediate-image-transfer recording method, the image transfer from the intermediate image transfer belt to the recording sheet is carried out with the application of pressure to both the recording sheet and the intermediate image transfer belt. In order to produce sufficient adhesion between the toner image and the recording sheet for use in practice, it is required to increase the above-mentioned pressure. However, in apparatus used in practice, there is a limit to the pressure that can be applied so that sufficient adhesion for use in practice cannot always be obtained and therefore the image transfer efficiency is low.
In conventional copying machines and printers, a heat roller or a heat plate is used as a heat source for fixing toner images, so that such conventional copying machines and printers have the shortcoming that power consumption is large.
Furthermore, developers in which silicone oil is used as the carrier liquid therefor have the shortcoming that they lack preservation stability because silicone oil is non-polar and therefore the dispersibility thereof is poor.
Furthermore, the use of silicone oil as a component for electrophotographic developers and recording materials has been conventionally proposed, for example, as disclosed in Japanese Laid-Open Patent Applications 3-171149, 3-171151 and 3-171152, in which the use of dimethyl silicone oil is specifically proposed.
However, cyclic polysiloxanes, for example, commercially available polysiloxanes (Trademark “KF994”, “KF995”, made by Shin-Etsu Chemical Co., Ltd.), have a low molecular weight and a low viscosity, so that the evaporation thereof is rapid, but have the problem of causing improper electric contact.
On the other hand, silicone oils having high molecular weight, such as KF96-10CS, 50CS, 100CS, 300CS, 1000CS, 5000CS, and 50000CS, are difficult to evaporate and therefore have no problem with respect to electric contact, but remain in copying paper, and cause image fixing performance to deteriorate, and ooze out of the copy paper, smearing the copy paper. When toner images are formed on an OHP (overhead projector) film, using the above silicone oils, the toner images are difficult to fix and become sticky.